There is a case where a main wing of an aircraft is used as a fuel tank capable of accommodating fuel. A fuel tank integrated with the main wing and having a wing structure of a liquid-tight structure in which oil does not leak is called an integral tank. The integral tank has a tendency to apply a composite material, for example, carbon fiber reinforced plastic (CFRP) thereto for the purpose of weight reduction. In the CFRP, carbon fibers are used as reinforcing materials and synthetic resin is used as a matrix.
In PTL 1, technique is disclosed which is an invention relating to a three-dimensional fiber-reinforced resin composite material and in which a selvage warp is configured by an electrically-conductive material having higher electrical conductivity than an in-plane direction yarn n order to apply electrical conductivity to a fiber-reinforced resin composite material without impairing productivity. Furthermore, in PTL 2, a technique is disclosed which is an invention relating to a prepreg and a carbon fiber reinforced composite material and includes electrically-conductive particles or fibers therein for the purpose of having both excellent impact resistance and electrical conductivity. Furthermore, in PTL 3, a technique is disclosed which is an invention relating to an improved composite material and includes electrically-conductive particles dispersed in polymeric resin therein for the purpose of having electrical conductivity and causing little or no weight increase compared to a standard composite material.